1. Field of the Invention
The present invention relates to improved alkylphenylsulfonate detergent compounds. In particular, it is concerned with a method of producing alkylphenylsulfonates having reduced 2-alkylphenylsulfonate isomer content.
2. Description of the Prior Art
Linear alkylbenzene sulfonates containing alkyl side chains of approximately 8 to 16 carbon atoms in length are used as surface active agents in commercial detergent compositions. The scientific literature on the subject has indicated that the average location on the alkyl chain of the phenyl group can have significant and important effects on the detergency properties of the sulfonate. It has been found that by minimizing attachment of the aromatic ring to the alkyl chain at the #2 and #3 carboon atom positions and maximizing the content of isomers having a more centrally located phenyl group is of particular benefit with respect to important detergency considerations. For instance, it has been demonstrated in studies of various dodecylphenylsulfonate isomers and mixtures that one may achieve significant increases in solubility, wetting power and foaming power merely by shifting the average phenyl group location to more internal positions on the alkyl chain. [Tjepkena et al., 5th World Petroleum Congress, Sect. 4, No. 21 (1959).]
Alkylphenylsulfonates are commonly prepared from alkylbenzene compounds, the position of the phenyl group in the intermediate being fixed during the initial reaction of benzene with the linear olefin. The production of the alkylbenzene is conventionally carried out in the presence of a Friedel-Crafts catalyst (e.g. AlCl.sub.3) to yield a mixture of all of the possible positional isomers. Attempts to reduce the external alkylbenzene isomer concentration (i.e. the 2-alkylbenzene), and thereby increase the relative concentration of the more desirable internal isomers (3-alkylbenzene; 4-alkylbenzene; etc.), have been reported, but only small reductions of the 2-alkylbenzene isomer content have been achieved.